Effect of longitudinal direct current magnetic field and heat treatment composite process on microstructure and mechanical properties of 2319 aluminum alloy WAAM

Abstract

Wire arc additive manufacturing (WAAM) had been proven to be viable for producing large metal components. However, its optimal performance had been limited by defects such as porosity, elemental segregation, and coarse grains. This study had introduced a composite process of applying a direct current magnetic field along with heat treatment to improve the microstructure and mechanical properties of the specimens, while also comparing changes under four different conditions. The results had indicated that applying a direct current magnetic field had expanded the arc and improved the macroscopic morphology. With a direct current of 2A, the specimen had the fewest macropores, making it the optimal parameter. After applying the magnetic field alone, porosity had significantly decreased, with a reduction of 0.43% compared to the blank specimen, and the average pore volume had decreased by 10.45mm³ compared to the blank specimen. After the composite application of the magnetic field and heat treatment, the proportion of recrystallization had increased, Cu element segregation had been notably improved, maximum texture strength had decreased, the proportion of high-angle grain boundaries had increased, and porosity improved by the magnetic field had increased. In terms of mechanical properties, the average microhardness had reached 206.2 HV, an increase of 104.36% compared to the blank specimen. The longitudinal average tensile strength had reached 387.9MPa, a 63.3% improvement over the blank specimen. Anisotropy had decreased, while elongation had been reduced.